Furnace humidifier

ABSTRACT

A humidifier unit for a warm air-heating system including a solenoid valve controlled water spray nozzle to be located in a portion of the air passage system through which warm air leaves a furnace to discharge a fine mist spray into the leaving air, a manually variable temperature-sensitive switch for sensing the air temperature in the passage, a sail switch activated by airflow through the air passage system, and an electrical circuit interconnecting the solenoid valve with the switches to operate the valve.

United States Patent Morrow [4 1 Jan. 18, 1972 [54] FURNACE HUMIDIFIER I 3,565,052 2/1971 Wallace ..l26/l 13 [72] Inventor: William B. Morrow, Winston-Salem, NC. FOREIGN PATENTS OR APPLICATIONS Assighw Aqua-Mist, Incorporated, Winston-Salem, 679,647 2/1964 Canada 126/1 13 Primary Examiner-Charles J. Myhre [22] Flled' 1970 Attorney-Mason, Fenwick & Lawrence [21] Appl. No.: 81,379

[57] ABSTRACT [52] US. Cl. ..126/113, 236/44 A A h midifier un f r a rm a r-heating system including a [51] Int. Cl solenoid valve controlled water spray nozzle to be located in a 58 Field of Search ..l26/ll3;236/44,44A portion of the air passage System through which Warm air leaves a furnace to discharge a fine mist spray into the leaving [56] References Cited air, a manually variable temperature-sensitive switch for sensing the air temperature in the passage, a sail switch ac- UNITED STATES PATENTS tivated by airflow through the air passage system, and an elec- Liben ..236/44 A X trical circuit interconnecting the solenoid valve with the switches to operate the valve.

9 Claims, 4 Drawing Figures PATENTEBJMWHIZ 3.635.210

SHEET 1 BF 2 INVENTOR WILLIAM B. Moranow ATTORNE Y8 PATENTEBJMHBBTZ 3,635,210

SHEET 2 [1F 2 I NVEN TOR WILLIAM B.MO

ATTORNEYS FURNACE HUMIDIFIER BACKGROUND AND OBJECTS OF THE INVENTION The present invention relates to a spray-type humidifier unit for attachment to or incorporation in warm air furnaces to in troduce adequate humidity into air being heated in the bonnet or plenum of the furnace prior toits discharge into the living space served by the fumace.

Heretofore, various means have been employed to supply water vapor to heated air in warm air-heating systems to humidify the air. These have customarily involved water-receiving receptacles in the bonnet or riser of a warm air furnace exposed to the warm air to evaporate water vapor into the air. Such devices become rapidly corroded or faulty and unreliable in operation. Spray-diffusing nozzle systems discharging a mist or fog of water droplets into the bonnet have also been used, usually with a target plate, collecting trough, or other facility to collect unvaporized discharge from the nozzle, but such devices have been difficult to control in such a way as to reliably prevent unwanted discharge, such as drips, from the nozzle, which accumulate in the furnace and produce corrosive precipitate solids adversely affecting the life or operation of the furnace. These spray humidifier systems have usually required complex special controls in addition to the usual controls for the furnace, and have been too complex to be suitable for installation by the ordinary homeowner as a do-it-yourself" type of installation. It is important for a simple installation which would be within the capacity of the normal homeowner to install, to provide a unit which involves only a few components to be installed on the furnace or ducting system, and to have provision for insuring that no spray can be discharged from the spray nozzle when the furnace blower is not operating.

The furnace humidifier system of the present invention is a spray-type humidifier having a spray discharge nozzle and control solenoid incorporated in one subassembly to be installed on the supply air riser or duct of a furnace, which latter unit also includesa temperature switch sensitive to the air temperature discharged from the furnace plenum. A second subassembly is a sail switch, which is activated responsive to air current flow, and which also is a humidistat in the preferred example, which is to be mounted on the cold air return duct of the furnace system. These two components are electrically connected to a 24 volt transformer which may be conventionally plugged into a conventional electrical supply receptacle to provide the electrical supply for the system. This spray-type humidifier operates only when the following two conditions a satisfied simultaneously (1) the temperature within the warm air plenum has reached a predetermined level, which is variable by the homeowner or installer, and (2) the air movement within the warm air plenum, as monitored in the return duct, has exceeded a predetermined level which is not variable. Because no drain is provided to take care of excess moisture discharged from the spray nozzle, both of the above conditions are necessary for proper operation, as the moisture is introduced directly into the airstream within the warm air plenum as a finely atomized spray.

BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is a schematic electrical diagram of the spray humidifier system of the present invention, with the spray nozzle, solenoid valve, and sail switch components associated therewith indicated diagrammatically and portions of the associated furnace shown in phantom lines;

FIG. 2 is an elevation view illustrating portions of a furnace with supply air and return air ducts and showing the components of the spray humidifier system assembled thereon;

FIG. 3 is a front elevation view of the spray nozzle unit, with the cover removed; and

FIG. 4 is a vertical section view taken along the line 4--4 of FIG. 3.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT Referring to the drawings, wherein like reference characters designate corresponding parts throughout the several figures, and particularly to FIG. 1 illustrating the spray humidifier unit in association with components of a gas :fired warm air furnace installation, the spray humidifier system of the present invention includes as its basic components a fog or mist producing nozzle 10 on the end of a water supply pipe 11 which extends from a substantially rectangular housing 12 and is regulated by a conventional solenoid valve 13 having a coil 13' supported within the housing. The housing 12, as illustrated in FIG. 2, is designated to be mounted on the hot air supply duct 14 of a furnace 15, with the water supply pipe 11 and nozzle 10 on the end thereof projecting through an opening cut in the side of the hot air supply duct 14 to discharge a spray of water into the hot airstream flowing through the supply duct 14. A

manually variable temperature-sensitive switch 16 is also provided in the housing 12, having the temperature sensitive elements thereof extending through the opening in the side of the hot air supply duct 14 to monitor the temperature of the air in the duct 14 in the region of the nozzle 10. A sail switch 17, which in the preferred embodiment is a humidistat/sail switch such as the H-49-B humidistat with sail switch produced by Honeywell, is mounted on the return air duct 18 of the furnace system with the arm for supporting the said mechanism extending through an opening cut in the wall of the return air duct 18 to locate the sail, indicated at 17a, in the return airstream to the furnace blower, indicated in phantom lines at 19. The temperature-sensitive switch 16 and the humidistat/sail switch 17 are electrically connected in series, as shown in FIG. 1, with the coil 13 of solenoid valve 13 and this series circuit combination is connected to the secondary of a 24 volt transformer 20 which is plugged into a conventional volt convenience outlet to provide the 24 volts supply in the secondary circuit including the switches 16 and 17 and the solenoid coil 13.

In the illustrated embodiment, the nozzle unit housing 12 is conveniently formed of a rear or base panel 21 on which the solenoid valve unit 13 and the temperature-sensitive switch 16 are mounted with the temperature-sensing element of the switch 16 and the supply pipe 11 extending to the nozzle 10 both projecting through openings provided in the panel 21. The panel 21 has vertical side flanges 22a, 22b projecting forwardly to form the sidewalls of the housing 12 and has shallow retaining flanges 23 along the horizontal top and bottom edges of the panel 21. A removable cover of channel configuration is indicated at 24 and defines the front wall and the top and bottom walls of the housing 12, the top and bottom wall portions having outwardly bent tabs 24a which interfit into slots in the retaining flanges 23 to removably assemble the cover 24 with the base panel 21.

Suitable openings are formed in the sidewall of the hot air supply duct 14, for example, a circular opening along the centerline thereof for the nozzle 10 and supply pipe 11 and a rectangular opening for the temperature-sensing element of the switch 16, after which the base panel 21 can be mounted on the sidewall of the supply duct 14 covering these openings by self-tapping screws. A rectangular opening appropriate to receive the sail supporting arm of the sail switch 17 is also cut in the sidewall of the return air duct 18 near the place where it joins the furnace and the humidistat/sail switch 17 is mounted over this opening by self-tapping screws. Copper or plastic tubing may then be connected to a saddle valve fitted on a cold water line and to the water inlet fitting 25 extending through a sidewall of the housing 12 from the solenoid valve 13, and electrical connections made between the humidistat/sail switch 17 and the terminal block 26 in the housing 12 and betweenthe terminal board and the transformer 20 to complete the electrical and plumbing connections for the system.

In the normal operation of the system, the conventional furnace thermostat in the space to be conditioned by the furnace calls for heat and electrically activates the furnace heating means, as by energizing the valve controlling the supply of fuel to the furnace burner, or energizing the electrical heating elements of the furnace, to produce heat within the furnace and began to increase the temperature within the warm air plenum. When the temperature within the warm air plenum reaches the ON-setting or cut-on temperature of the conventional furnace fan control, the furnace blower 19 is energized, producing airflow through the return duct 18, the blower l9, and the bonnet or plenum of the furnace and discharge of heated air through the supply duct 14. The temperature within the warm air plenum then reaches the ON-setting of the humidifier temperature-sensitive switch 16, which is set to a predetermined level slightly higher than the ON-setting of the furnace fan control. This causes the spray unit to be activated, since the sail switch 17 is already closed by the airflow through the return duct 18 produced by operation of the blower 19, and the humidifier temperature-sensitive switch 16 is now closed completing the circuit to the coil 13' of the solenoid valve 13 controlling supply to the nozzle 10. When the furnace thermostat becomes satisfied, or high limit cutoff in the bonnet switch is reached, the furnace burner or heater is turned off, while the furnace blower continues operation. The temperature within the warm air plenum falls to the OFF-setting of the humidifier temperature-sensitive switch 16, opening the supply circuit to the solenoid valve 13 to close this valve and therefore turn the spray unit off. The temperature within the warm air plenum then falls to the OFF-setting of the furnace fan control, turning off the furnace blower 19.

With the above-described control arrangement, a humidifier system is provided which insures that the humidifier will not come on until the plenum has reached at least the blower cuton temperature, it will shut down before the plenum has reached, at minimum, the blower cutoff temperature, and the humidifier cannot come on before the blower comes on. The maximum or outer limits of operation are defined by the sail switch 17, which prevents the humidifier from operating unless the furnace blower is operating. Within these outer limits, spray duration can be varied, by proper setting of the temperature-sensitive switch 16.

The humidifier temperature-sensitive switch 16 is variable, in the preferred embodiment, having an OFF-temperature range of 90-l20 F. and an ON-temperature range of l-l 35 F., with a differential of l5+ F. This differential is narrower than that normally found in furnace fan controls, to enable the humidifier spray to be turned off at a higher temperature than (i.e., before) the furnace blower even though the spray was activated at a higher temperature than (i.e., after) the blower.

The duration of the spray is controlled by varying the OFF- setting of the temperature-sensitive switch 16. In general a decrease in the OFF-setting will cause an increase in the spray duration. A variable OFF-setting isneeded to adapt the unit to different operating temperature levels within the warm air plenum of furnaces of differing designs.

A temperature-sensitive switch alone could not be safely relied upon to assure that the spray would be activated only when the furnace blower is operating. If a fixed or factory set temperature-sensitive switch (without a variable OFF-setting) were used as the sole spray control, the ON-temperature selected at the factory could, on a given furnace, be lower than the ON-setting of the furnace blower control. If a variable temperature'sensitive switch were used as the sole spray control to avoid the possible problem described in the preceding sentence, the problem of improper setting by the installer is introduced as the installer could set the humidifier spray to come on before the blower and/or to remain on after the furnace blower shuts off. By providing the sail switch 17 which completes the circuit through the temperature-sensitive switch 16 and spray valve 13 only when sufficient air current is flowing to signify that the furnace blower is operating, humidifier operation is absolutely limited to the period during which air is actually moving through the warm air plenum. The sail switch 17 also acts as a fail-safe device, to prevent spray operation when furnace blower failure occurs, as for example, when the belt on a belt-driven blower fails, and even when the temperature-sensitive switch 16 fails in an ON-condition, spray operation would be limited to periods when the furnace blower is operating. The sail switch 17 does not have to include a humidistat as a part of the switch unit, but since a humidistat is commercially available in combination with the sail switch, use of the humidistat/sail switch combination is preferred.

The above-described group of units provides a humidifier system which is well adapted to installation by a homeowner. To mount the spray unit housing 12 and sail switch 17 on the supply duct 14 and return duct 17 he merely cuts openings in these ducts at the appropriate locations guided, for example, by templates which can be supplied with the units, and secures the housing and sail switch in position by self-tapping screws. The water supply inlet fitting 25 may then be connected to a nearby cold water pipe, by for example, drilling the cold water pipe and installing a saddle valve in the drilled opening and connecting it by conventional compression fittings and copper or plastic tubing, and preferably a line strainer, to the fitting 25. The wires connecting to the sail switch 17 and transformer 20 are led through grommets in holes in the sides 22a, 22b of the housing 12 and connected to appropriate terminals of the terminal block 26, and the transformer 20 may then be plugged into the electrical outlet, indicated at 28, and retained in this position by a slotted or forked tab 20a held by the usual center mounting screw for the faceplate of the electrical outlet.

What is claimed is:

l. A humidifier unit for a warm air-heating system of the type including a furnace to heat air for supply to a living space, air passage means for circulation of air through said furnace to said living space including a furnace plenum chamber, heating means in the furnace for heating air in the plenum chamber, an electrically driven blower for propelling air through the plenum chamber and air passage means, a first electrical furnace control circuit including a room thermostat responsive to temperature in the living space for operating the heating means, and a second electrical furnace control circuit including a blower control bonnet switch responsive to the temperature in said plenum chamber having a selected blower cut-on temperature and a lower blower cutoff temperature for operating the blower during the period the temperature in the plenum chamber is above the cut-on and cutoff temperature levels; the humidifier system comprising a water spray nozzle to be located in said air passage means for discharging a fine mist spray therein during circulation of air therethrough for humidifying the circulating air, a supply valve controlling water supply to said spray nozzle, a solenoid coil for opening and closing said supply valve, a manually variable temperature-sensitive switch for sensing the air temperature in the region of said air passage means occupied by said spray nozzle and adjustable to a range of cut-on and cutoff temperature settings near and above the cu t-on and cutoff temperature levels of conventional bonnet switches for furnaces, a sail switch having a sail member to be located in said air passage means activated by air currents flowing therethrough when said blower is operating to close an electrical circuit through said sail switch, and electrical circuit means connecting said sail switch and said temperature-sensitive switch in series circuit relation with said solenoid coil and with an electrical supply source for opening said supply valve only when said sail switch and said temperature-sensitive switch are in closed circuit condition.

2. A warm air-heating system as defined in claim 1, wherein said air passage means includes a hot air supply duct directly adjoining said furnace for passage of heated air from the furnace and a cool air return duct connected to said furnace for return of cool air to said blower, said temperature-sensitive switch being mounted on said hot air supply duct adjacent said furnace for sensing the temperature of the air immediately upon entering said hot air supply duct from said furnace, and said sail switch being mounted on said cold air return duct with the sail located within said duct to respond to airflow therein.

3. A warm air-heating system as defined in claim 1, wherein said air passage means includes a hot air supply duct directly adjoining said furnace for passage of heated air from the furnace and a cool air return duct connected to said furnace for return of cool air to said blower, said temperature-sensitive switch and spray nozzle being mounted on said hot air supply duct adjacent said furnace for sensing the temperature of the air immediately upon entering said hot air supply duct from said furnace and spraying water mist into the air at said location, and said sail switch being mounted on said cold air return duct with the sail located within said duct to respond to airflow therein.

4. A system as defined in claim 2 wherein said sail switch includes a humidistat which is adjustable to selected humidity levels and completes an electrical circuit therethrough only when the sail is activated by airflow through said return duct when the blower is operating and the humidity concurrently does not exceed a selected level.

5. A system as defined in claim 3 wherein said sail switch includes a humidistat which is adjustable to selected humidity levels and completes an electrical circuit therethrough only when the sail is activated by airflow through said return duct when the blower is operating and the humidity concurrently does not exceed a selected level.

6. A warm air-heating system of the type comprising a furnace to heat air for supply to a living space, air passage means for circulation of air through said furnace to said living space including a furnace plenum chamber, heating means in the furnace for heating air in the plenum chamber, an electrically driven blower for propelling air through the plenum chamber and air passage means, a first electrical furnace control circuit including a room thermostat responsive to temperature in the living space for operating the heating means for heating the air during the period the thermostat occupies a demand condition, a second electrical furnace control circuit including a blowercontrol switch communicating with said plenum chamber and responsive to the air temperature therein having a selected blower cut-on temperature and a lower blower cutoff temperature for operating the blower during the period the temperature in the plenum chamber is above the cut-on and cutoff temperature levels, a humidifier water spray nozzle located in said air passage means for discharging fine mist spray therein during circulation of air therethrough for humidifying the circulating air, a water supply conduit having a solenoid valve controlling water supply to said spray nozzle, a solenoid coil for opening and closing said valve, a manually variable temperature-sensitive switch for sensing the air temperature in the region of said air passage means occupied by said spray nozzle and adjustable to a range of cut-on and cutoff temperature settings near and above the cut-on and cutoff temperature levels of conventional bonnet switches for furnaces, a sail switch having a sail member located in said air passage means activated by air currents flowing therethrough when said furnace blower is operating to close an electrical circuit through said sail switch, and electrical circuit means connecting said sail switch and said temperature-sensitive switch in series circuit relation with said solenoid coil and with an electrical supply source for opening said valve means only when said sail switch and said temperature-sensitive switch are in closed circuit condition.

7. A warm air-heating system as defined in claim 6, wherein said air passage means includes a hot air supply duct directly adjoining said furnace for passage of heated air from the furnace plenum chamber and a cool air re'tum duct connected to said furnace for return of cool air to said blower, said temperature-sensitive switch and spray nozzle being supported by a housing mounted on said hot air supply duct adjacent said furnace with the spray nozzle and portions of the temperaturesensitive switch extending into the interior of the duct for sensing the temperature of the heated air immediately entering said hot air supply duct from said furnace and spraying water mist into the heated air at said location, and said sail switch being mounted on said cold air return duct with the sail located within said duct to respond to airflow therein.

8. A system as defined in claim 6 wherein said sail switch includes a humidistat which is adjustable to selected humidity levels and completes an electrical circuit therethrough only when the sail is activated by airflow through said air passage means when the blower is operating and the humidity concurrently does not exceed a selected level.

9. A system as defined in claim 7 wherein said sail switch includes a humidistat which is adjustable to selected humidity levels and completes an electrical circuit therethrough only when the sail is activated by airflow through said return duct when the blower is operating and the humidity concurrently does not exceed a selected level. 

1. A humidifier unit for a warm air-heating system of the type including a furnace to heat air for supply to a living space, air passage means for circulation of air through said furnace to said living space including a furnace plenum chamber, heating means in the furnace for heating air in the plenum chamber, an electrically driven blower for propelling air through the plenum chamber and air passage means, a first electrical furnace control circuit including a room thermostat responsive to temperature in the living space for operatinG the heating means, and a second electrical furnace control circuit including a blower control bonnet switch responsive to the temperature in said plenum chamber having a selected blower cut-on temperature and a lower blower cutoff temperature for operating the blower during the period the temperature in the plenum chamber is above the cut-on and cutoff temperature levels; the humidifier system comprising a water spray nozzle to be located in said air passage means for discharging a fine mist spray therein during circulation of air therethrough for humidifying the circulating air, a supply valve controlling water supply to said spray nozzle, a solenoid coil for opening and closing said supply valve, a manually variable temperature-sensitive switch for sensing the air temperature in the region of said air passage means occupied by said spray nozzle and adjustable to a range of cut-on and cutoff temperature settings near and above the cut-on and cutoff temperature levels of conventional bonnet switches for furnaces, a sail switch having a sail member to be located in said air passage means activated by air currents flowing therethrough when said blower is operating to close an electrical circuit through said sail switch, and electrical circuit means connecting said sail switch and said temperature-sensitive switch in series circuit relation with said solenoid coil and with an electrical supply source for opening said supply valve only when said sail switch and said temperature-sensitive switch are in closed circuit condition.
 2. A warm air-heating system as defined in claim 1, wherein said air passage means includes a hot air supply duct directly adjoining said furnace for passage of heated air from the furnace and a cool air return duct connected to said furnace for return of cool air to said blower, said temperature-sensitive switch being mounted on said hot air supply duct adjacent said furnace for sensing the temperature of the air immediately upon entering said hot air supply duct from said furnace, and said sail switch being mounted on said cold air return duct with the sail located within said duct to respond to airflow therein.
 3. A warm air-heating system as defined in claim 1, wherein said air passage means includes a hot air supply duct directly adjoining said furnace for passage of heated air from the furnace and a cool air return duct connected to said furnace for return of cool air to said blower, said temperature-sensitive switch and spray nozzle being mounted on said hot air supply duct adjacent said furnace for sensing the temperature of the air immediately upon entering said hot air supply duct from said furnace and spraying water mist into the air at said location, and said sail switch being mounted on said cold air return duct with the sail located within said duct to respond to airflow therein.
 4. A system as defined in claim 2 wherein said sail switch includes a humidistat which is adjustable to selected humidity levels and completes an electrical circuit therethrough only when the sail is activated by airflow through said return duct when the blower is operating and the humidity concurrently does not exceed a selected level.
 5. A system as defined in claim 3 wherein said sail switch includes a humidistat which is adjustable to selected humidity levels and completes an electrical circuit therethrough only when the sail is activated by airflow through said return duct when the blower is operating and the humidity concurrently does not exceed a selected level.
 6. A warm air-heating system of the type comprising a furnace to heat air for supply to a living space, air passage means for circulation of air through said furnace to said living space including a furnace plenum chamber, heating means in the furnace for heating air in the plenum chamber, an electrically driven blower for propelling air through the plenum chamber and air passage means, a first electrical furnace control circuit including a room thermostat responsive to temperature in The living space for operating the heating means for heating the air during the period the thermostat occupies a demand condition, a second electrical furnace control circuit including a blower control switch communicating with said plenum chamber and responsive to the air temperature therein having a selected blower cut-on temperature and a lower blower cutoff temperature for operating the blower during the period the temperature in the plenum chamber is above the cut-on and cutoff temperature levels, a humidifier water spray nozzle located in said air passage means for discharging fine mist spray therein during circulation of air therethrough for humidifying the circulating air, a water supply conduit having a solenoid valve controlling water supply to said spray nozzle, a solenoid coil for opening and closing said valve, a manually variable temperature-sensitive switch for sensing the air temperature in the region of said air passage means occupied by said spray nozzle and adjustable to a range of cut-on and cutoff temperature settings near and above the cut-on and cutoff temperature levels of conventional bonnet switches for furnaces, a sail switch having a sail member located in said air passage means activated by air currents flowing therethrough when said furnace blower is operating to close an electrical circuit through said sail switch, and electrical circuit means connecting said sail switch and said temperature-sensitive switch in series circuit relation with said solenoid coil and with an electrical supply source for opening said valve means only when said sail switch and said temperature-sensitive switch are in closed circuit condition.
 7. A warm air-heating system as defined in claim 6, wherein said air passage means includes a hot air supply duct directly adjoining said furnace for passage of heated air from the furnace plenum chamber and a cool air return duct connected to said furnace for return of cool air to said blower, said temperature-sensitive switch and spray nozzle being supported by a housing mounted on said hot air supply duct adjacent said furnace with the spray nozzle and portions of the temperature-sensitive switch extending into the interior of the duct for sensing the temperature of the heated air immediately entering said hot air supply duct from said furnace and spraying water mist into the heated air at said location, and said sail switch being mounted on said cold air return duct with the sail located within said duct to respond to airflow therein.
 8. A system as defined in claim 6 wherein said sail switch includes a humidistat which is adjustable to selected humidity levels and completes an electrical circuit therethrough only when the sail is activated by airflow through said air passage means when the blower is operating and the humidity concurrently does not exceed a selected level.
 9. A system as defined in claim 7 wherein said sail switch includes a humidistat which is adjustable to selected humidity levels and completes an electrical circuit therethrough only when the sail is activated by airflow through said return duct when the blower is operating and the humidity concurrently does not exceed a selected level. 